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Random number generator example.

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This commit is contained in:
Oliver Dille 2012-09-07 22:43:10 +02:00
parent e99896120b
commit 099a5626db
3 changed files with 118 additions and 0 deletions
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25
examples/stm32/f4/stm32f4-discovery/random/Makefile Normal file
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##
## This file is part of the libopencm3 project.
##
## Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
##
## This library is free software: you can redistribute it and/or modify
## it under the terms of the GNU Lesser General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## This library is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU Lesser General Public License for more details.
##
## You should have received a copy of the GNU Lesser General Public License
## along with this library. If not, see <http://www.gnu.org/licenses/>.
##
BINARY = random
LDSCRIPT = ../stm32f4-discovery.ld
include ../../Makefile.include

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examples/stm32/f4/stm32f4-discovery/random/README Normal file
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------------------------------------------------------------------------------
README
------------------------------------------------------------------------------
This example randomly blinks the green LED on the ST STM32F4DISCOVERY eval board.

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examples/stm32/f4/stm32f4-discovery/random/random.c Normal file
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/*
* This file is part of the libopencm3 project.
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libopencm3/cm3/common.h>
#include <libopencm3/stm32/f4/rcc.h>
#include <libopencm3/stm32/f4/gpio.h>
#include <libopencm3/stm32/f4/rng.h>
static void rcc_setup(void)
{
rcc_clock_setup_hse_3v3(&hse_8mhz_3v3[CLOCK_3V3_120MHZ]);
/* Enable GPIOD clock for onboard leds. */
rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPDEN);
/* Enable rng clock */
rcc_peripheral_enable_clock(&RCC_AHB2ENR, RCC_AHB2ENR_RNGEN);
}
static void rng_setup(void)
{
/* Enable interupt */
/* Set the IE bit in the RNG_CR register. */
RNG_CR |= RNG_CR_IE;
/* Enable the random number generation by setting the RNGEN bit in the RNG_CR
register. This activates the analog part, the RNG_LFSR and the error detector.
*/
RNG_CR |= RNG_CR_EN;
}
static void gpio_setup(void)
{
/* Setup onboard led */
gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO12 | GPIO13);
}
/* Tried to folow the guidelines in the stm32f4 user manual.*/
static u32 random_int(void)
{
static u32 last_value=0;
static u32 new_value=0;
u32 error_bits = 0;
error_bits = RNG_SR_SEIS | RNG_SR_CEIS;
while (new_value==last_value) {
/* Check for error flags and if data is ready. */
if ( ((RNG_SR & error_bits) == 0) && ( (RNG_SR & RNG_SR_DRDY) == 1 ) )
new_value=RNG_DR;
}
last_value=new_value;
return new_value;
}
int main(void)
{
int i,j;
rcc_setup();
gpio_setup();
rng_setup();
while(1){
u32 rnd;
rnd = random_int();
for(i=0;i!=32;++i){
if ( (rnd & (1 << i))!=0 )
gpio_set(GPIOD, GPIO12);
else
gpio_clear(GPIOD, GPIO12);
/* Delay */
for(j=0;j!=5000000;++j)
__asm__("nop");
}
}
}